I don't think 2.6'ish GHz is out of the question. Perhaps even 2.7-2.8. My 6600XT routinely runs at 2.6+ GHz, so it isn't unfeasible.16CU N24 is supposedly ~141 mm^2 built using 6nm process, Videocardz.
If we compare It to 24CU N14 with a die size of 158 mm^2, then It doesn't look so good, 1/3 less CU, 1/2 memory controller, +16MB IC and you save only 10% by using a better process.
To have the same TFLOPs as a fully unlocked N14, you would need to have 50% higher clocks, in other words ~2.7-2.8GHz. Against RX 5500XT you only need ~38% higher clocks, in other words ~2.45-2.55GHz.
These cards aren't targeted at 1440p. The 6600XT would be my minimum for that. In fact it is my minimum. 4K? 6800 as a minimum. But I'm not taking out a mortgage for one of those.Another problem is only 4GB Vram and at 1440p only 64bit GDDR6 will also be a bottleneck, we can also see this with RX 6600XT at 4K.
The only real positive about N24 should be the power consumption, hopefully It will be <=75W.
With regards to bandwidth, don't underestimate that Infinity Cache, and assuming 16GHz GDDR6 @ 64bit is still 128GB/s of bandwidth. Upping to the newer 20GHz would be 160GB/s. Samsung actually makes 24GHz capable GDDR6, so 192GB/s is theoretically possible. Should be plenty for 1080p. Even if we're talking GTX1060 class performance, that's still a competent 1080p card. Of course, you have to maybe turn down a setting or two, and forget about ray tracing, but should still be good.